1. Field of the Invention:
This invention relates in general to refrigerant recovery devices, and in particular to an apparatus that will recover two incompatible types of refrigerant.
2. Description of the Prior Art:
A typical prior art refrigerant recovery apparatus has a pair of hoses that will connect to the high and low pressure sides of the compressor of an air conditioning system. The recovery unit has an expansion valve which expands any liquid components being recovered into a gaseous refrigerant. An evaporator adds heat to the cold gaseous refrigerant. A compressor connects to the evaporator for compressing the refrigerant in the gaseous state. The hot gaseous refrigerant at the exit of the compressor passes through a condenser, where it is condensed to a warm liquid. The warm liquid refrigerant flows into a storage tank for later use. Filters located in the unit filter foreign matter such as particles and water moisture. Additionally, oil will be separated by an oil separator in the recovery unit. The oil will be measured so that the same amount can later be reintroduced.
Many recovery units also have the capability of recharging the air conditioning system with refrigerant. The recharging features include a vacuum pump for evacuating the system to a level substantially below the vacuum level achieved by the operation of the recovery unit compressor. Then, a valve is opened to flow refrigerant from the storage container into the air conditioning system.
The prior art type of refrigerant was harmful to the ozone layer if released into the atmosphere. Recent regulations will prohibit the future manufacture of the prior art type, which typically was called "R-12". New air conditioning systems for vehicles now employ a different refrigerant, called "R-134A". That refrigerant is much less harmful to the ozone layer than the prior refrigerant, thus will eventually replace the prior refrigerant type.
Meanwhile, however, there are millions of vehicles and other types of air conditioning systems using the prior art type of refrigerant. These systems need to be maintained and repaired. Also, many of the systems will eventually be retrofitted so that they can use the new type of refrigerant. A retrofit generally requires new seals and hoses.
The existing refrigerant recovery units will not recover both R-12 and R-134A because these refrigerants are incompatible. The oil contained within the R-12 refrigerant would contaminate the hoses and seals of the recovery unit such that the recovery unit would not be able to recover and clean R-134A refrigerant. Repair shops need to have the ability to recover both types of refrigerants. In the prior art, this requires purchasing two stand alone recovery units, adding additional equipment expense.